1. Field of the Invention
The invention relates to a method and system for electronically controlling various operational parameters such as revolutions per minute (RPM), ignition spark timing, cylinder timing and gear shifting of an internal combustion engine. Specifically, the present invention allows such control via an interface that has an easy to read, word based menu system and method for easily changing related engine operational parameters.
2. Description of the Related Art
Conventional, mechanical methods of controlling engine parameters have been employed to govern the maximum revolutions per minute (RPM) the crankshaft of an engine rotates, set ignition spark timing and to control gear shifting.
In the past, revolutions per minute that the crankshaft rotates were limited by controlling the amount of fuel delivered for consumption. Modem, spark internal combustion engines typically utilize the ignition system to control RPM of the engine. Once the engine has reached the maximum RPM allowed, the ignition system will cut the electrical impulse to the spark plug, thereby preventing the spark plug from firing in the cylinder and consumption of fuel. Various methods have been employed to sequentially or randomly interrupt the firing order of the spark plugs. Adjustable RPM limiters typically utilize dial or resistor-type chips on the ignition box itself to set the maximum RPM allowed during operation. More complex RPM limiters allow for more than one RPM limit to be set for controlling RPM during various conditions or stages of operation. Once the maximum RPM of the first set dial or chip is reached, the engine is allowed to reach the next maximum RPM set by the next dial or chip and so on. One problem associate with these types of RPM limiters is that the adjustable dials are typically small and difficult to change in order to prevent the dial from rotating due to engine and chassis vibration. Furthermore, systems that utilize resistor chips are limited by what chips the user has and both systems are limited by the predetermined increments of the dials or the chips.
To increase performance and accuracy of timing in high revolutions per minute engines, electronic ignition systems were developed. As RPM increase, the timing cycles for delivering a spark to the cylinder becomes very compressed and further rotating parts, crank and camshaft, may bend under stress, thereby adding inaccuracies in conventional, mechanical timing systems. Electronic ignition systems overcome these mechanical inaccuracies by typically triggering the spark timing off of the flywheel or balancer on the crankshaft or the camshaft, thereby eliminating the need to mechanically adjust the timing at the camshaft and distributer.
For peak efficiency, the fuel must be ignited in the cylinder on the up stroke of the piston as the fuel mixture is under pressure to give the flame created by the spark time to travel across the cylinder and ignite the fuel mixture. For example, a spark timed to arrive at X degrees advance, before top dead center (TDC) of the piston, may actually spark many degrees before or after the set timing. Improper timing or inaccurate sparking may cause detonation in which the fuel ignites while the piston is at the early phase of the upward travel, pre-ignition, or later in the downward stroke which may damage the valve train assembly, piston, connect rod or in the extreme, the crankshaft.
Typically electronic ignition systems ramp up to a set degree of ignition timing as RPM increase. For example, with ignition timing set at 30 degrees advance, the actual ignition timing may begin from start up (0 RPM) at 10 degrees advance and linearly increase until the timing reaches 30 degrees advance at thousands of RPM later. One problem associated with electronic ignition timing systems, is the inability to set degrees ignition timing as a function of RPM or the ignition system may only allow changing slope of the linear ramp up timing, thereby preventing the engine from operating at peak efficiency or maximum power. Furthermore, these systems do not allow the changing of the ignition timing as a function of an event such as a gear shift.
Sudden changes in cylinder pressure due to the boost of a turbo charger, the injection of nitrous oxide into the fuel mixture, gear shifts or the combination thereof, present another problem for ignition timing. As cylinder pressure changes, the optimum ignition timing point may also change. Electronic ignitions systems have been developed to monitor cylinder or inlet manifold pressure and compensate for these changes, but are limited by the sampling rates of the electronics used and typically do not let the user input timing adjustments. Furthermore, in high performance applications, the timing adjustments cannot be made quickly to compensate for the rapid changing conditions.
To achieve peak engine performance in a racing application, the racer or crew chief may alter engine components and settings to find the optimum combination. Ignition timing is one such setting that must be optimized for each engine combination. The racer often finds the optimum ignition timing setting by adjusting the timing and making a run with the racecar to determine its effect. This process cannot only be time consuming, but also tedious due the physical requirements of manually changing the ignition timing.
Furthermore, varying weather conditions will also affect the performance of these types of engines. Any change in temperature, barometric pressure, humidity or combination thereof will affect the performance characteristics of the engine. Ignition timing is one parameter the racer may change to compensate for these changes in weather conditions.
Also, the racer may alter ignition timing to control the performance of the racecar. For example, in some drag racing applications were the race is run on an ET (elapsed time) index, the racer may desire to slow the ET of the racecar using ignition timing. By retarding the ignition timing, the racer can, in effect, de-tune the engine and elongate the elapsed time of the run. Thus, it is desirable to have an ignition timing system capable of allowing the user to pre-select timing changes as a function of RPM or events.
Another physical limitation of mechanical ignition systems is the inability to control individual cylinder timing. In a conventional mechanical ignition system, the timing is set in relation to TDC of one cylinder. Typically, the first cylinder that fires is used to physically set when the rotor of the distributor makes contact with the terminal which supplies the current to the spark plug when that piston is at TDC, or at a particular degree of timing before TDC, i.e., rotor phasing. Once the rotor is phased, all cylinders will then fire in relation to this pre-determined phasing. The timing can be further adjusted by rotating the entire distributor and shaft and with a timing light, monitoring the timing at the balancer.
In high RPM engines, it may be advantageous to have one or more cylinders firing before or after the pre-selected timing to optimize the efficiency for the conditions of each individual cylinder. For example, with the timing set at 30 degrees advance (before TDC), one cylinder which creates a higher pressure than the rest may burn more efficiently if fired at 25 degrees advance. Thus, for peak efficiency and maximum power applications, it is advantageous to be able to control individual cylinder timing. Although this may be achieved by some real-time using computer systems, these systems may be too slow for high RPM engines and may not be allowed by race sanctioning bodies and further, they do not allow the user to select and specify the individual cylinder timing.
In high performance engines, as well as all engines, there exists an optimum RPM to shift from one gear to the next. It is well known in the automotive industry to use a xe2x80x9cshift lightxe2x80x9d to signal the driver to manually shift gears once the correct RPM has been reached for that particular gear shift. Such shift lights are typically controlled by an electronic system which monitors the tachometer and sends a signal to illuminate shift light once a particular RPM determined by a computer or a dial-type switch has been reached. In an automatic transmission, this signal can also be used to activate an automatic shifter. Typically, these gear shift systems are separate and independent of the electronic ignition timing systems and, thus, two electronic xe2x80x9cboxesxe2x80x9d must be placed on the car.
One attempt to combine both an ignition timing and gear shift controller is the QUICKSHOT(trademark) Programmer and ProStrip Annihilator ignition system developed by Holley Performance Products. Due to the small physical size, the programmer uses a two digit or letter code to identify the parameter and then removes the code and displays the first two digits of value for that particular parameter. Thus, the user must either memorize or use a reference aids to identify the code for the parameter. However, this may become very inconvenient for the racer in the field where the level of surrounding activity can be extremely disruptive due to the limited time between runs, to refer to a reference manual or code sheets while attempting to make adjustments. Moreover, if the codes are confused and the wrong engine control parameter is inadvertently changed, misfiring, or incorrect shifting may result which can cause significant engine damage. Furthermore, due to the limited display on the programmer, approximately 1.25 inches by 1 inch, only one individual parameter code can be viewed and selected at a time. Also, this system does not provide an efficient, user-friendly method for controlling individual cylinder ignition timing.
Accordingly, an interface that allows a wide variety of engine operational parameters to be adjusted via an easy to recognize engine parameter terms on its display. In this regard, a system is needed which allows engine parameter changes to be made quickly without the need of reference materials and provide safeguards to prevent for inadvertent changes in one engine control parameter which may dampen performance or result in engine damage. Furthermore, it would be desirable to provide a programmable engine control system capable of controlling multiple functions such as gear shifting, individual cylinder timing and RPM controls in one box thereby reducing the number of electronic units needed in the car.
The present invention provides a unique approach to controlling engine control parameters by providing a menu driven system which limits which engine parameters the user may change at one time. The present system and method utilizes a menu driven hand-held programmer, or in the alternative a computer, which directs the user through various engine control parameters using easy to recognize terms.
In racing application such as drag racing, racers are won and lost by ten thousandths of a second. Therefore, optimum performance must be achieved during each run to increase efficiency and gain consistency while preventing damage to the engine. One method of increasing consistency and protecting the engine is to limit the RPMs (xe2x80x9crevlimitxe2x80x9d) the engine turn during specific events of the drag race. For example, the racer may desire to control the maximum RPM the engine can reach during the burn-out portion of the race. A burn-out is a procedure which involves either rolling through water and spinning the tires at high RPM once on dry pavement or spinning the tires in the water while using the front brakes to hold the car. This spinning warms the surface temperature of the tire which increases the stickiness of the rubber for a greater grip at the starting line. However, during the burn-out, the engine RPM may rise significantly because the tires are spinning instead of moving the racecar under a load. Therefore, in high RPM engines, it is advantageous to limit the RPMs the engine may turn to prevent catastrophic failure of the engine.
Another portion of a drag race the racer may desire to control RPMs is during the launch stage. After the driver has completed the burn-out, the driver will roll the front tires into a set of light beams, thereby xe2x80x9cstagingxe2x80x9d the car. Once staged, the racer will either activate a transbrake which holds the transmission in first and reverse or engage the clutch of a manual transmission and hold the car using a hand brake. The driver will then xe2x80x9cmatxe2x80x9d the accelerator pedal to increase the engine RPMs. This allows the engine to be at high RPMs when the car is launched. Again, without controlling the maximum RPMs the engine may reach, the engine may reach extremely high RPMs which may result in engine component failure. Thus, it is desirable to have a revlimiter for the launch portion of the race. Similarly, the driver may desire to control the maximum RPMs the engine may reach over the entire run of the race to prevent xe2x80x9cred-liningxe2x80x9d and engine damage.
The racer will typically make these types of revlimit adjustments, as well as gear shift settings and others, before and after a run of the car at the track to achieve the desired performance. However, the racer must be able to quickly input the adjustments due to the short time available between runs. Accordingly, it can be extremely confusing and inconvenient for the racer to have to refer to reference manuals or code-key sheets to input adjustments to engine control parameters such as required by the previously described system. Furthermore, a light-weight programmer which may be easily held and quickly viewed is required so that the racer can make adjustments on both the car and the programmer without have to carry a computer to the car or walk back and forth between the computer and the racecar.
The present invention provides easy-to-read indicia which are word-based allowing the racer to make the desired adjustments by scrolling through menus and switch screens depending on the words read on the screen. This eliminates the needs for referring back and forth between the screen and a code book. The interface displays the indicia in English or other foreign languages may be used tailored to the preferred language of the user. Furthermore, many racers collect data from the run using computer-based electronics, down-load the data after the run and view the data on a computer to determine what adjustments are needed. In one form, the invention provides the racer the option to view engine control parameters such as individual cylinder timing and an ignition timing run curve that represents timing changes over the entire run on a computer display in graphical representations. This allows the racer to quickly view the information without scrolling through excess data and allows the racer to make quick decisions and changes based on the data displayed. Also, the user may program a single value for controlling the revolutions per minute at the launch of the race by using another interface, a small module with rotary dials which can be mounted in the cockpit of the racecar.
The present invention allows for maximum RPM controls to be set by selecting one menu screen which displays selection choices of maximum RPM controls as used in drag racing applications. For example, the user may select and input the maximum RPM setting during the burn-out, thereby eliminating the need for tedious resistor-chips or dials. Instead, the present invention allows inputting the actual RPM number in one hundred degree increments using a keyboard on the small, approximately 3.5 inches by 3 inches, hand-held programmer and easily viewed on the 1 inch by 2 inches screen. Furthermore, these RPM controls may only be changed while in the RPM menu thereby preventing inadvertent changes.
Ignition timing can also be controlled at various stages of the drag race after the initial timing has been set, e.g., the user can retard the ignition timing during the launch of the race car from the starting line and select a ramp of the ignition timing curve as the RPM increase. Furthermore, the menu system also allows for retarding the ignition timing as a function of RPM by numerically inputting the RPM and degree of retard timing necessary for that RPM. This is especially helpful for racecars using a turbo charger or those which utilize nitrous oxide. In the alternative, the user may select a launch or run curve which allows the user to specify the ramp-up of the ignition timing during the launch of the racecar from the starting line or during the entire run. Again, the user simply inputs the RPM value and the degree of timing for that value and continues to input those values over the duration of the run or the launch.
The present invention can also provide independent timing retard of individual cylinders. While in the cylinder degree menu, the user may input the degrees of timing retard for each individual cylinder by selecting the cylinder and numerically inputting the degrees of timing retard from 0 to 5 degrees in 0.1 degree increments. This allows the user to optimize the performance of each individual cylinders. For example, if a cylinder, or more if needed, is creating a higher internal pressure than the rest, that cylinder will burn more efficiently if fired earlier. Thus, the present invention allows the user to set ignition timing for all cylinders and, at the same time, change the timing of one cylinder.
The gear shifting parameters which can be used to illuminate a gear shift light or to automatically control a shifter may also be controlled. The user may select up to five gear shift parameters by numerically inputting the RPM per shift light (or shift) indicator. Further, ignition timing can also be retarded in response to a change in gear. Thus, the need for a separate gear shift controller is eliminated by combining a revolution limiter, ignition timing and gear shift controller in one system.
The programmable engine controller utilizes a non-volatile memory to store the inputted parameters. Thus, once the hand-held programmer or a computer connection of a computer is removed, the engine control parameters are stored in the non-volatile memory in the electronic controller. Further, these values may only be changed when programmer or computer is interfaced with the controller.
The details of the invention, together with further objects and advantages of the invention, are set forth in the detailed description which follows. The precise scope of the invention is defined by the claims annexed to and forming a part of this specification.